Power transmitting chain with floating bushing and method of manufacture

ABSTRACT

At least one floating metallic bushing acts as an intermediate bearing member between roller link subassemblies and link pin subassemblies of a power chain. At least one master connection link is held in place by means of a readily disconnectable spring clip. Manufacturing steps include placing a roller link subassembly over open link pin ends of adjacent link pin subassemblies, inserting at least one metallic floating bushing over each pin end and closing each link pin subassembly by fixing link pin members on the open link pin ends of each link pin subassembly.

United States Patent Paul [ Feb.22,1972

[54] POWER TRANSMITTING CHAIN WITH FLOATING BUSHING AND METHOD OFMANUFACTURE [72] inventor: William T. Paul, l-lolyoke, Mass.

[73] Assignee: North American Rockwell Corporation,

Pittsburgh, Pa.

[22] Filed: Oct. 29, 1970 [21] App1.No.: 85,053

[52] US. Cl ..74/254, 74/258 [51] Int. Cl ..Fl6g 13/02 [58] Field ofSearch ..74/254, 258, 255 R [56] References Cited UNITED STATES PATENTS617,716 1/1899 Caldwell ..74/258 14 jfi i/ A 1,121,053 12/1914 Terry..74/258 2,775,156 12/1956 lmseetal ..74/254X Primary Examiner-LeonardH. Gerin Attorney-John R. Bronaugh, Floyd S. Levison, E. Dennis 0-Connor and Richard A. Speer [5 7] ABSTRACT At least one floatingmetallic bushing acts as an intermediate bearing member between rollerlink subassemblies and link pin subassemblies of a power chain. At leastone master connection link is held in place by means of a readilydisconnectable spring clip. Manufacturing steps include placing a rollerlink subassembly over open link pin ends of adjacent link pinsubassemblies, inserting at least one metallic floating bushing overeach pin end and closing each link pin subassembly by fixing link pinmembers on the open link pin ends of each link pin subassembly.

7 Claims, 5 Drawing Figures POWER TRANSMITTING CHAIN WITH FLOATINGBUSHING AND METHOD OF MANUFACTURE BACKGROUND OF THE INVENTION Thisinvention relates to improvements in power transmitting chains andparticularly to an improved floating bushing used as an intermediatebearing member between a roller link unit and a link pin unit. Powertransmitting chains are commonly driven by toothed sprocket wheels andare used in many heavy industrial applications. A typical application istheir use as the power takeoff chain of agricultural equipment. Anothercommon application is the use of power transmitting chains in the powertrain of chain conveyors. Often, power transmitting chains have readilydisconnectable master link units to enable chain disconnection forchain-shortening or repair purposes.

This invention further relates to a method of manufacturing a powertransmitting chain containing master link units and intermediatefloating bushings.

DESCRIPTION OF THE PRIOR ART The use of a floating bushing as anintermediate bearing member between a roller bushing link subassemblyand a link pin subassembly to reduce excessive interlink friction isknown in the prior art. Previous prior art teachings sought to takeadvantage of the self-lubrication properties of solid plastic floatingbushings having generally low friction surfaces such as a Teflon(polytetrafluoroethylene) bushing. However, the use of plastic floatingbushings are totally unsuited for certain power chain applications. Forexample, plastic bushings cannot be used where the power chain issubjected to the high temperatures and heavy loads found in a chaindriven conveyor kiln environment. Another major disadvantage which is anobject of this invention to overcome is the premature failure of theplastic bushing under load. This breakdown of the bushing under loadtakes several forms. Heat generated by articulation of the fixed rollerbushing with respect to the outer surface of the plastic floatingbushing and by the articulation of the link pin with respect to theinner surface of the plastic bushing increases as load increases. Thenonmetallic bushing under such heat and pressure has a tendency todeform when subjected to prolonged use and to extrude out of the rollerbushing in which it is seated. The fatigue strength of the nonmetallicfloating bushing presents a limitation to its useful life in most powerand in particular in heavy load transmitting chains. Further, lateralflexing pressures of the chain can cause the chain to twist under thetensions produced, thereby deforming the nonmetallic floating bushing.This creates deleterious looseness and/or binding of the roller linksubassemblies and the link pin subassemblies. This breakdown of theprior art nonmetallic bushing causes chain elongation which leads tochain repair or replacement. Undesirable down time of expensiveequipment to effect chain repair is another problem of which it is anobject of this invention to minimize.

SUMMARY OF THE INVENTION This invention provides for an improvedfloating bushing in the form of a metallic bushing. A major advantage ofthe metallic bushing is that it is directed towards reducing therelative motion between the roller link subassembly and the pin linksubassembly, thereby lessening the frictional heat generated byarticulation and reducing the wear of the surfaces in contact. The priorart nonmetallic bushing was directed towards friction reduction byhaving a plastic selflubricating material between the pin and fixedbushing.

Another major advantage is that the metallic bushing has increased wearlife and reliability compared to the nonmetallic bushing.

Another major advantage is that the metallic bushing has greater fatigueresistance, dimensional stability under load and adverse environmentalconditions than the nonmetallic bushing. This invention furthercontemplates the use of plural floating metallic bushings in whichreduction of the relative motion between mating parts during jointarticulation is accomplished by the use of a floating metallic bushingbeing mounted within a second floating bushing. This invention alsocontemplates the use of plural floating metallic bushings coaxiallyaligned in a train so as to abut each other.

It is another object of this invention to provide a readily detachablemaster link connection. Master links are commonly placed on powertransmitting chains to enable chain connection and disconnection to aidin chain repair or in changing a chain length. Quick connection ordisconnection is accomplished by means of a spring clip abutting anouter side of a pin link member.

In another embodiment it is contemplated that a floating metallicbushing may be coated on either or both its inner and outer surface witha thin plastic coating. This laminated floating bushing combinesself-lubrication with greater deformation resistance than theall-plastic floating bushing.

This invention further relates to a method of manufacturing a powertransmission chain using metallic floating bushings, said methodcomprising the steps of forming roller link subassemblies, as forexample, by press fitting the ends of two roller bushings into twospaced roller link plates having pitch holes therefor, forming link pinsubassemblies, as for example, by press fitting a link pin into eachpitch hole of a two pitch hole link member, placing a first roller linksubassembly over one link pin and a second roller link subassembly overthe other pin, and then inserting an intermediate bearing member, suchas floating metallic bushing, into each of the roller bushings, and thenclosing the link pin subassembly by placing a top two pitch hole linkmember over both exposed link pin ends to thereby limit axial movementof the roller link subassemblies.

Other features of the invention will become apparent from the followingmore detailed description and from the accompanying drawing, in which:

FIG. 1 is a plan view ofa roller chain in partial section;

FIG. 2 is a side view of the chain of FIG. 1;

FIG. 3 is an exploded end view of the chain of FIG. 1;

FIG. 4 is a sectional view of a modified form of floating metallicbushing taken on the line A-A of FIG. 1 looking in the directionindicated by the arrows; and

FIG. Sis an end view ofconnection pin 25.

Referring now to the drawings, and in particular to FIGS. 13, there isillustrated a length of power transmitting chain 10 which can be drivenby toothed drive sprocket wheels (not shown). Such sprocket wheels arecommonly used with various power takeoff machinery drives. Powertransmission chain 10 is composed of a series of roller link units orsubassemblies interconnected by link pin units or subassemblies. Eachroller link subassembly comprises two spaced apart roller bushings 24connected by inner roller link members 20 and 22. These bushings 24 arefixedly attached into pitch holes extending through the inner rollerlink members 20 and 22 as by a press fit. Both the roller bushings andthe roller link members can be made of a suitable grade of steel.

Two spaced standard rivet-type link pins 21 are fixedly attached neartheir ends to outer pin link members 12 and 14 as by a press fit. Atleast one intermediate bearing member in the form of floating metallicbushing 32 is placed in each roller bushing 24 and in coaxialrelationship to a link pin 21. Floating metallic bushing 32 is placed ineach roller bushing prior to closing the link pin subassembly.

As best viewed in FIGS. 1 and 2, a master connection link is formed byholding outer pin link members between the inner surface of the heads ofconnection pins 25 and a spring clip 18. The outer pin link members arethe same as the outer pin link members 12 and 14 held by link pins 21.Connection pin 25 is normally fixedly attached with respect to the outerpin link members as by press fitting. However, connection pin 25 couldalso be mounted so as to freely rotate with respect to the outer pinlink members. As shown in FIG. 5, the end opposite the head end ofconnection pin 25 has a grooved recess 26. Spring clip 18 has an innerslot portion 19 (FIG. 2) which engages a grooved recess 26 at each slotend. One end of the spring clip 18 is split to allow fitting of thespring clip over the connection pin ends. Such master link units areused to allow quick chain disconnection to effect chain repair,replacement of subassembly units or changes in chain length. Two springclips 18 could be used in place of a single clip and two connection pinheads by having a grooved recess 26 adjacent each pin end.

The selection of the metal to be used in the metallic bushing 32 dependson a variety of factors. Major criteria to be considered would includethe chains environment of use, i.e., temperature and load conditions andcost differences in manufacture. The proper selection of the metal islargely dependent on the particular application.

Floating bushing 32 can be made of a suitable steel, such as plainsteel, carbon steel or a stainless steel. A carburized and hardenedsteel can also be used. in a preferred embodiment, shown in FIGS. 1-3,bushing 32 can be made of a stainless steel in the 300 series or the 400series. The 300 series is preferred in applications calling for hightemperatures and/or corrosion resistance. The 400 series is heattreatable and is preferred in applications calling for greater strengththan the 300 series. A more expensive and stronger stainless steel, suchas the precipitation hardening 17-4 and 17-7 family may be used in powertransmission chains requiring unusual resistance to heat, corrosion andhigh work load conditions. Typical applications would be in suchenvironments as conveyor chain drives in bakeries and metalheat-treating kilns. Particularly corrosive conditions are often presentin oil and water quenching kilns.

It is contemplated that other high-strength metals and metal alloyscould also be employed as the floating bushing material.

It is further contemplated in another embodiment that more than onemetallic floating bushing could be provided depending upon variousfactors such as size of the chain and load conditions.

One form of plural floating bushings would have one floating bushingmounted within a second floating bushing so as to be in a coaxialconcentric relationship to each other. The innermost floating bushingcould be seated on a link pin 21 and inserted into the outermostfloating bushing seated within a fixed roller bushing 24. Although morecostly than a single floating bushing, double floating bushings wouldachieve greater reduction in internal friction generated by articulationof the roller link subassembly and the pin link subassembly.

Another form of plural floating bushings would be to align two or moreof them in coaxial train relationship within a single roller bushing 24.

It is also possible to use a sintered metallic bushing which has theadvantage of providing a self-lubricating effect while still capable ofuse in applications not contemplated by the prior art plastic bushings.Floating bushings 32 can also be made of cast iron to take advantage ofthe self-lubricating qualities of the higher carbon content of suchirons.

A severe limitation to the known all-plastic bushing is its tendency todeform and extrude under operational loading pressures. The HQ. 4embodiment illustrates a laminated floating bushing characterized by thefact that the core portion 34 is metallic while the surface portions 33and 35 are thin bonded layers of plastic known to have goodselflubricating properties, such as vinyl, nylon, Teflon or silicone.Both Teflon and silicon have the added advantage of having lowcoefflcients of friction. The laminated floating bushing thus combinesthe strength of a metallic core with the self-lubrication qualities ofplastic films. The thin bonded plastic layer will not extrude and deformunder the pressure loads at which the conventional solid plastic bushingfails. it is also possible to bond only one surface of the metalliccore.

The process manufacturing the previously described power transmittingchain involves the following steps: An integral fixed roller linksubassembly is prepared by fixedly attaching two roller bushings 24 intothe pitch holes of spaced apart inner roller link members 20 and 22. Aplurality of these roller link subassemblies are thus made up in thismanner. Both floating bushings 32 and roller bushings 24 can be formedinto their cylindrical hollow shapes by curling flat sheets or strips ofsteel into tubular form and then cutting for length size. It should beunderstood that both bushings can also be formed by other conventionalmethods of making bushings, as for example, by extrusion processes. Twostandard rivet type link pins 21 are fixedly attached to pitch holesprovided in bottom outer pin link member 14, as by a press fit. Oneroller link subassembly is then placed over one of the link pins 21while a second roller link subassembly identical to the first is placedover the outer link pin 21. The roller link subassemblies can be placedeither sequentially or simultaneously. At least one floating bushing 32is then placed inside of the roller bushings 24 having link pins 21extending therethrough. It is also possible to place the floatingbushings 32 on the link pins 21 before placing the fixed roller bushingsubassemblies. The linking of the roller link subassemblies is thencompleted by fixedly attaching, as by press fitting, a top outer pinlink member 12 having pitch holes identical to those of bottom outer pinlink member 14 to the free ends of link pins 21. Axial movement of theroller bushing and the floating bushing is thus limited. if a masterlink is desired, then connection pins 25 are used in place of link pins21. After the top outer pin link member is placed over the connectionpins a spring clip 18 having an inner slot portion 19 split at one endis inserted into alignment with grooved recesses 26 provided on eachconnection pin.

Having thus described the invention in rather complete detail, it willbe understood that these details need not be strictly adhered to andthat various changes and modifications may be made, all falling withinthe scope of the invention as defined by the following claims.

lclaim:

l. A method of manufacturing a power transmitting chain link assemblycomprising:

a. fixedly attaching a roller bushing into each pitch hole of a twopitch hole first roller link member;

b. fixedly attaching a two pitch hole roller link member over saidroller bushings in spaced substantially parallel relationship to saidfirst roller link member, thereby forming a first roller linksubassembly;

c. forming a second roller link subassembly in the manner set forthabove;

d. fastening a link pin into each pitch hold of a bottom two pitch holepin link member;

e. placing said first roller link subassembly over one of said link pinssuch that said link pin extends through one of the roller bushings ofsaid first roller ink subassembly;

f. placing said second roller link subassembly over the other of saidlink pins such that said other link pin extends through one of theroller bushings of the second roller link subassembly;

g. inserting at least one floating bushing over each of said link pinssuch that each floating bushing is coaxially seated with respect to oneof said roller bushings;

h. placing a top pin member having two pitch holes over the tops of saidlink pins thereby linking said first and second roller linksubassemblies; and

. retaining said top pin link member on the said link pins therebylimiting axial displacement of the roller link subassemblies.

2. A power transmitting chain link assembly comprising a combination ofinterconnected roller link subassemblies and pin link subassemblies;wherein each of said roller link subassemblies comprises a pair ofspaced apart inner roller link members, roller bushings and at least onefloating metallic bushing mounted within each of said roller bushings,said roller link members having pitch holes adjacent their ends whichreceive said roller bushings thereby holding them in spacedrelationship;

each of said pin link subassemblies having a pair of pin link membersspaced outwardly of said inner roller link members and pins attached tothe ends of said pin link members to form an integral pin linksubassembly; each of said claim 2 wherein said floating metallic bushinghas at least one bearing surface coated with a thin self-lubricatingplastic film.

6. The power transmitting chain link assembly according to claim 2wherein said floating metallic bushing has selflubricating sinteredmetallic surfaces.

7. The power transmitting chain link assembly according to claim 4wherein each of said pins has at least one recessed groove adjacent anend, said spring clip means engaging said recessed groove of each pin.

UNHED TATFS PATENT @FHQE UERTWMATE WP 6GRREQTEN Patent 3,643,517 DatedFebruary 22, 1972 Imentms) WILLIAM T, PAUL It: is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

Column 4 Claim 1, line 44, change "hold" to read "hole" line 48, change"ink" to read "link line 56, after "pin" insert ---link---.,

Signed and sealed this 30th day of January 1973.

(SEAL) Attest:

EDWARD M.JELEIGHER JRo ROBERT GOTTSCHALK Attesting; Officer Commissionerof Patents

1. A method of manufacturing a power transmitting chain link assemblycomprising: a. fixedly attaching a roller bushing into each pitch holeof a two pitch hole first roller link member; b. fixedly attaching a twopitch hole roller link member over said roller bushings in spacedsubstantially parallel relationship to said first roller link member,thereby forming a firsT roller link subassembly; c. forming a secondroller link subassembly in the manner set forth above; d. fastening alink pin into each pitch hold of a bottom two pitch hole pin linkmember; e. placing said first roller link subassembly over one of saidlink pins such that said link pin extends through one of the rollerbushings of said first roller ink subassembly; f. placing said secondroller link subassembly over the other of said link pins such that saidother link pin extends through one of the roller bushings of the secondroller link subassembly; g. inserting at least one floating bushing overeach of said link pins such that each floating bushing is coaxiallyseated with respect to one of said roller bushings; h. placing a top pinmember having two pitch holes over the tops of said link pins therebylinking said first and second roller link subassemblies; and i.retaining said top pin link member on the said link pins therebylimiting axial displacement of the roller link subassemblies.
 2. A powertransmitting chain link assembly comprising a combination ofinterconnected roller link subassemblies and pin link subassemblies;wherein each of said roller link subassemblies comprises a pair ofspaced apart inner roller link members, roller bushings and at least onefloating metallic bushing mounted within each of said roller bushings,said roller link members having pitch holes adjacent their ends whichreceive said roller bushings thereby holding them in spacedrelationship; each of said pin link subassemblies having a pair of pinlink members spaced outwardly of said inner roller link members and pinsattached to the ends of said pin link members to form an integral pinlink subassembly; each of said pins interconnecting adjacent roller linksubassemblies by passing through at least one of said metallic floatingbushings thereby allowing said floating bushings to rotate with relationto said pins.
 3. The power transmitting chain link assembly according toclaim 2 wherein said pins are fixedly attached to the ends of said pinlink members.
 4. The power transmitting chain link assembly according toclaim 2 wherein at least one of said pin link members is attached tosaid pins by spring clip means.
 5. The power transmitting chain linkassembly according to claim 2 wherein said floating metallic bushing hasat least one bearing surface coated with a thin self-lubricating plasticfilm.
 6. The power transmitting chain link assembly according to claim 2wherein said floating metallic bushing has self-lubricating sinteredmetallic surfaces.
 7. The power transmitting chain link assemblyaccording to claim 4 wherein each of said pins has at least one recessedgroove adjacent an end, said spring clip means engaging said recessedgroove of each pin.